#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
	int n,t;
	cin>>n>>t;
	if(t<10)
	{
		for(int i = 0;i<n;i++) cout<<t;
		cout<<endl;
	}
	else 
	{
		if(n==1) cout<<"-1"<<endl;
		else 
		{
			for(int i = 0;i<n;i++)
			{
				if(i==0) cout<<"1";
				else cout<<"0";
			}
			cout<<endl;
		}
	}
}
